Food spoilage
- 1. SPOILAGE OF FOOD MADE BY- SAIJJAL SURI BSC. FOOD SCIENCE AND TECH. SYS ID- 2019006898
- 2. Food spoilage means the original nutritional value, texture and flavour of food is damaged and the food becomes harmful and unsuitable to eat. Food spoilage can be a result of - Insect damage - Physical injury - Enzymatic degradation - Microbial activity Characteristics of spoiled food are - Unpleasant smell - Unpleasant taste - Colour changes - Texture changes - Mould growth
- 3. MAIN CAUSES OF FOOD SPOILAGE 1) PHYSICAL CHANGES – Temperatures, water activity, mechanical effects It is caused by inappropriate transport, handling and storage. 2) BIOLOGICAL FACTORS – Microbiological Bacteria, yeasts and moulds. 3) MICROBIOLOGICAL – Rodents, insects, birds, parasites Non- microbial or enzymatic changes usually involving oxygen oxidation processes.
- 4. EFFECTS OF FOOD SPOILAGE 1) CHANGES IN NUTRITIONAL VALUE – Decomposition of proteins, carbohydrates and vitamins 2) CHANGES IN ORGANOLEPTIC FEATURES – Changes in colour, flavour, taste and presence of unpleasant odour. 3) UNWHOLESOME EFFECTS – Biogenic amines, toxins Metabolites of microorganisms Pathogen microbes
- 5. SPOILAGE SIGNS 1) ODOUR – Breakdown of proteins E.g. : rotten egg smell 2) SLIMINESS – Primarily due to surface accumulation of microbial cells and also be a manifestation of tissue degradation. 3) DISCOLORATION – Mould on bread, blue and green mould on citrus fruit and cheese. 4) SOURING – Production of acid E.g. : sour milk from production of lactic acid
- 6. There are two types of spoilage : -Microbial spoilage -Non- Microbial spoilage Based on rate of spoilage products are classified into : 1) HIGHLY PERISHABLE -Meat, fish, poultry, egg, milk, most fruits and vegetables 2) SEMI- PERISHABLE -Potatoes, apples 3) NON- PERISHABLES -Sugar, flour, dry beans
- 7. SOURCES OF MICROORGANISMS The primary sources of microorganisms in food include : Soil Water Plant and plant products Food utensils Intestinal tracts of man and animals Food handlers Animal skin Air and dust
- 8. FACTORS AFFECTING MICROBIAL GROWTH 1) INTRINSIC FACTORS : These are inherent in the food. They include – Hydrogen ion concentration (pH) Moisture content Nutrient content of food Antimicrobial properties Biological structures
- 9. 2) EXTRINSIC FACTORS : These are the factors external to the food that affect the microbial growth. They include- Temperature of storage Presence and concentration of gases in the environment Relative humidity of food storage environment
- 10. FOOD PRESERVATION Food preservation is the process of treating and handling food, with an aim to stop or slow down its spoilage while maintaining its nutritional value, texture and flavour. Food preservation methods either kill microbes or prevent their growth. Food preservation principles: Two general principles are employed in food preservation process- 1) INHIBITION PRINCIPLE In this principle, food preservation is achieved by inhibition of growth and multiplication of microorganisms. 2) KILLING PRINCIPLE In this principle, spoilage microorganism are destroyed (killed) in the food, and the food protected against subsequent contamination by being enclosed in an air tight container.
- 11. SOME METHODS OF FOOD PRESERVATION ARE : Boiling Dehydration Freezing and refrigeration Canning Using chemical preservatives Using sugar, salt, oil or vinegar Pasteurization
- 12. HOW TO REDUCE FOOD SPOILAGE Remove expired or spoiled food Store food in refrigerator or freezer according to their needs Prevent mould growth in the refrigerator Keep some foods separate to prevent spoilage
- 13. Thankyou